Bone Abstracts

Background: JDM is a systemic autoimmune inflammatory myopathy consisting of symmetric proximal muscle weakness, heliotrope and/or malar rash, Gottron’s papules, nailfold capillary changes, myalgias, arthralgias, dysphonia, dysphagia, fever, anorexia, and calcinosis. Hypoparathyroidism can present with signs of hypocalcemia (numbness, tingling, bronchospasm, seizure, or tetany). Causes of HP include postoperative, autoimmune (isolated or in autoimmune polyglandular syndromes (APS) (AIRE gene in APS1)) or syndromic (i.e. DiGeorge syndrome). Autoimmune HP has been associated with many antibodies; both NALP5 and Ca sensing receptor antibodies may functionally impair PTH release (instead of causing gland destruction). Myopathy without weakness has been reported as a presenting feature of HP. Both disorders have been seen with other autoimmune disease (AD) in the same person, but have not been described together.

Presenting problem: A 15 year old girl presented with progressive leg and arm weakness and leg and trunk rash. Muscle biopsy confirmed dermatomyositis and laboratory evaluation revealed elevated inflammatory markers and hypocalcemia (6.7 mg/dl).

Clinical management: She was managed with IV methylprednisolone (MP) and methotrexate for JDM. Ca ranged from 7.2–8.5 mg/dl until MP frequency decreased, when Ca dropped to 6.1 mg/dl and she was started on oral calcium and ergocalciferol. Hypocalcemia persisted (6 mg/dl, iCa 0.81 mM) and was associated with hyperphosphatemia (6.7 mg/dl), and HP (PTH 5 pg/ml). She required IV Ca and has been managed with oral Ca, calcitriol, and sevelamer. We suspect autoimmune HP; AIRE gene studies were normal. JDM and HP have had a waxing and waning course. Much disease activity has been unpredictable; however, she has developed hypercalcemia and variable Ca, calcitriol and sevelamer needs which appear to correlate inversely with the degree of immune suppression needed for JDM.

Discussion: JDM and HP are autoimmune diseases which each carry significant morbidity and affect overall and health-related quality of life (QOL). To our knowledge, this is the first reported case of JDM and HP coexisting in a single patient. In this patient, the complex effects on QOL seem to be exacerbated by possible interaction of the diseases themselves and/or changes in one disease due to treatment of the other.

Disclosure: The authors declared no competing interests.